Method for controlling combustion mode transitions in an internal combustion engine

Abstract

An engine is transitioned from a first combustion mode to a second combustion mode. Phase and lift of the intake and exhaust valves are sequentially adjusted corresponding to intake air cylinder volume and residual gas cylinder volume corresponding to the first and second combustion modes.

1. Method for operating an internal combustion engine including variable cam phasing mechanisms and multi-step valve lift mechanisms operative to control phase and lift of intake and exhaust valves, the internal combustion engine selectively operative in a first combustion mode and a second combustion mode, the method comprising:
 commanding transitioning engine operation from the first combustion mode to the second combustion mode; 
 adjusting phasings of the intake valves and the exhaust valves corresponding to a first intake air cylinder volume and a first residual gas cylinder volume; 
 switching magnitude of lift of one of the intake valves and the exhaust valves corresponding to the second combustion mode; 
 adjusting phasings of the intake valves and the exhaust valves corresponding to a second intake air cylinder volume and a second residual gas cylinder volume; 
 switching magnitude of lift of the other of the intake valves and the exhaust valves corresponding to the second combustion mode; and 
 adjusting phasings of the intake valves and the exhaust valves corresponding to a preferred intake air cylinder volume and a preferred residual gas cylinder volume for operating in the second combustion mode. 
 
     
     
       2. The method of  claim 1 , wherein the first combustion mode comprises a spark-ignition combustion mode and the second combustion mode comprises a controlled auto-ignition combustion mode;
 the method further comprising: 
 adjusting phasing of the intake valves to achieve a maximum phasing; 
 adjusting phasing of the exhaust valves to achieve a maximum phasing; 
 switching magnitude of lift of the exhaust valves from a high-lift valve open position to a low-lift valve open position when a residual gas cylinder volume corresponding to the low-lift valve open position is less than a residual gas cylinder volume corresponding to the high-lift valve open position; 
 adjusting phasing of the intake valves to achieve an effective cylinder volume corresponding to the intake valve closing at a low-lift valve open position that is equal to the effective cylinder volume corresponding to the intake valve closing at a high-lift valve open position; and 
 switching magnitude of lift of the intake valves from a high-lift valve open position to a low-lift valve open position. 
 
     
     
       3. The method of  claim 1 , wherein the first combustion mode comprises a controlled auto-ignition combustion mode and the second combustion mode comprises a spark-ignition combustion mode;
 the method further comprising: 
 adjusting phasing of the exhaust valves to achieve the first selected intake air cylinder volume; 
 adjusting phasing of the exhaust valves to achieve the first selected residual gas cylinder volume; 
 switching magnitude of lift of the intake valves from a low-lift valve open position to a high-lift valve open position when an effective cylinder volume corresponding to the intake valve closing at the low-lift valve open position is equal to the effective cylinder volume corresponding to the intake valve closing at the high-lift valve open position; 
 adjusting phasing of the intake valves to a maximum phasing; 
 switching magnitude of lift of the exhaust valves from a low-lift valve open position to a high-lift valve open position when an effective cylinder volume corresponding to the exhaust valve closing at the low-lift valve open position is less than the effective cylinder volume corresponding to the exhaust valve closing at the high-lift valve open position. 
 
     
     
       4. Method for controlling operation of an internal combustion engine including variable cam phasing mechanisms and two-step valve lift control mechanisms operative to control phasing of intake and exhaust valves and operative to control magnitude of lift of the intake and exhaust valves to one of two discrete steps, the method comprising:
 commanding switching the magnitude of lift of the intake and exhaust valves from first discrete steps to second discrete steps; 
 adjusting phasings of the intake valves and the exhaust valves corresponding to a first intake air cylinder volume and a first residual gas cylinder volume; 
 switching magnitude of lift of one of the intake valves and the exhaust valves from the first corresponding discrete step to the second corresponding discrete step; 
 adjusting phasings of the intake valves and the exhaust valves corresponding to a second intake air cylinder volume and a second residual gas cylinder volume; and 
 switching magnitude of lift of the other of the intake valves and the exhaust valves from the first corresponding discrete step to the second corresponding discrete step. 
 
     
     
       5. The method of  claim 4 , further comprising adjusting phasings of the intake valves and the exhaust valves corresponding to a preferred intake air cylinder volume and a preferred residual gas cylinder volume subsequent to switching magnitude of lift of the other of the intake valves and the exhaust valves from the first corresponding discrete step to the second corresponding discrete step. 
     
     
       6. Method for controlling a direct injection internal combustion engine selectively operating in a plurality of engine operating modes and comprising a cylinder, an exhaust valve, and an intake valve, the intake and exhaust valves each selectively operating in a plurality of valve lift settings and selectively operating with a variable valve actuation timing, the method comprising:
 monitoring a current engine operating mode comprising a current exhaust valve lift setting and a current intake valve lift setting; 
 monitoring a desired engine operating mode comprising a desired exhaust valve lift setting and a desired intake valve lift setting; 
 determining a valve transition scheme based upon the current exhaust valve lift setting, the current intake valve lift setting, the desired exhaust valve lift setting, and a desired intake valve lift setting; and 
 utilizing the valve transition scheme to transition from the current engine operating mode to the desired engine operating mode; 
 wherein the valve transition scheme comprises: 
 a substantially continuous change to an effective cylinder volume for air throughout the transition; and 
 a substantially continuous change to an effective cylinder volume for residual gas throughout the transition. 
 
     
     
       7. The method of  claim 6 , wherein utilizing the valve transition scheme comprises selectively controlling the variable valve actuation timing of each of the valves and the valve lift settings of each of the valves. 
     
     
       8. The method of  claim 6 , wherein the substantially continuous change to the effective cylinder volume for air comprises transitioning from the current intake valve lift setting to the desired intake valve lift setting at a point calibrated to provide a substantially equal effective cylinder volume for air for the current intake valve lift setting and the desired intake valve lift setting. 
     
     
       9. The method of  claim 6 , wherein the substantially continuous change to the effective cylinder volume for residual gas comprises transitioning from the current exhaust valve lift setting to the desired exhaust valve lift setting at a point calibrated to provide a substantially equal effective cylinder volume for residual gas for the current exhaust valve lift setting and the desired exhaust valve lift. 
     
     
       10. The method of  claim 6 , wherein the current engine operating mode is a spark-ignition mode; and
 wherein the desired engine operating mode is a homogeneous charge compression-ignition mode. 
 
     
     
       11. The method of  claim 10 , wherein the current exhaust valve lift setting is a first high-lift setting;
 wherein the current intake valve lift setting is a second high-lift setting; and 
 wherein determining the valve transition scheme further comprises:
 transitioning the exhaust valve from the first high-lift setting to a first low-lift setting, comprising:
 controlling the variable valve actuation timing of the exhaust valve to a setting close to a maximum positive overlap position for the exhaust valve; 
 controlling the variable valve actuation timing of the intake valve to a setting close to a maximum positive overlap position for the intake valve; 
 comparing an estimated effective cylinder volume for residual gas corresponding to the variable valve actuation timing of the exhaust valve at the setting close to the maximum positive overlap position at the first high-lift setting to an estimated effective cylinder volume for residual gas corresponding to the variable valve actuation timing of the exhaust valve at the setting close to the maximum positive overlap position at the first low-lift setting; and 
 controlling the exhaust valve from the first high-lift setting to the first low-lift setting if the estimated effective cylinder volume for residual gas at the first high-lift setting is greater than the estimated effective cylinder volume for residual gas at the first low-lift setting; and 
 
 subsequently transitioning the intake valve from the second high-lift setting to a second low-lift setting, comprising:
 controlling the variable valve actuation timing of the intake valve away from the setting close to the maximum positive overlap position; 
 comparing an estimated effective cylinder volume for air corresponding to the variable valve actuation timing of the intake valve at the second high-lift setting to an estimated effective cylinder volume for air corresponding to the variable valve actuation timing of the intake valve at the second low-lift setting; and 
 controlling the intake valve from the second high-lift setting to the second low-lift setting if the estimated effective cylinder volume for air at the second high-lift setting is substantially equal to the estimated effective cylinder volume for air at the second low-lift setting. 
 
 
 
     
     
       12. The method of  claim 10 , wherein the current exhaust valve lift setting is a first high-lift setting;
 wherein the current intake valve lift setting is a second high-lift setting; and 
 wherein determining the valve transition scheme further comprises:
 transitioning the exhaust valve from the first high-lift setting to a first low-lift setting, comprising:
 controlling the variable valve actuation timing of the intake valve to a setting close to a maximum positive overlap position for the intake valve; 
 controlling the variable valve actuation timing of the exhaust valve to a calibrated setting corresponding to an estimated effective cylinder volume for residual gas with the exhaust valve in the first high-lift setting being substantially equal to an estimated effective cylinder volume for residual gas with the exhaust valve in the first low-lift setting; and 
 controlling the exhaust valve from the first high-lift setting to the first low-lift setting; and 
 
 subsequently transitioning the intake valve from the second high-lift setting to a second low-lift setting, comprising:
 controlling the variable valve actuation timing of the intake valve to a calibrated setting corresponding to an estimated effective cylinder volume for air with the intake valve in the second high-lift setting being substantially equal to an estimated effective cylinder volume for air with the intake valve in the second low-lift setting; and 
 controlling the intake valve from the second high-lift setting to the second low-lift setting. 
 
 
 
     
     
       13. The method of  claim 10 , wherein the current exhaust valve lift setting is a first high-lift setting;
 wherein the current intake valve lift setting is a second high-lift setting; and 
 wherein determining the valve transition scheme further comprises:
 decreasing the effective cylinder volume for air and increasing the effective cylinder volume for residual gas by:
 controlling the variable valve actuation of the exhaust valve and the variable valve actuation of the intake valve toward a maximum positive overlap position for each of the valves to a calibrated setting whereat the exhaust valve can be changed from the first high-lift setting to a first low-lift setting with substantially zero change to the effective cylinder volume for residual gas; 
 changing the exhaust valve from the first high-lift setting to the first low-lift setting; 
 controlling the variable valve actuation of the exhaust valve away from the maximum positive overlap position to increase the effective cylinder volume for residual gas; 
 controlling the variable valve actuation of the intake valve away from the maximum positive overlap position to a calibrated setting whereat the intake valve can be changed from the second high-lift setting to a second low-lift setting with substantially zero change to the effective cylinder volume for air; 
 changing the intake valve from the second high-lift setting to the second low-lift setting; and 
 controlling the variable valve actuation of the exhaust valve based upon the desired engine operating mode to control the effective cylinder volume for air and the effective cylinder volume for residual gas. 
 
 
 
     
     
       14. The method of  claim 10 , wherein the current exhaust valve lift setting is a first low-lift setting;
 wherein the current intake valve lift setting is a high-lift setting; and 
 wherein determining the valve transition scheme comprises:
 transitioning the intake valve from the high-lift setting to a second low-lift setting, comprising:
 controlling the variable valve actuation timing of the intake valve to a calibrated setting corresponding to an estimated effective cylinder volume for air with the intake valve in the high-lift setting being substantially equal to an estimated effective cylinder volume for air with the intake valve in the second low-lift setting; and 
 controlling the intake valve from the high-lift setting to the second low-lift setting. 
 
 
 
     
     
       15. The method of  claim 6 , wherein the current engine operating mode is a homogeneous charge compression-ignition mode; and
 wherein the desired engine operating mode is a spark-ignition mode. 
 
     
     
       16. The method of  claim 15 , wherein the current intake valve lift setting is a first low-lift setting;
 wherein the current exhaust valve lift setting is a second low-lift setting; and 
 wherein determining the valve transition scheme further comprises:
 transitioning the intake valve from the first low-lift setting to a first high-lift setting, comprising:
 controlling the variable valve actuation timing of the intake valve toward a setting close to a maximum positive overlap position for the intake valve; 
 comparing an estimated effective cylinder volume for air corresponding to the variable valve actuation timing of the intake valve at the first low-lift setting to an estimated effective cylinder volume for air corresponding to the variable valve actuation timing of the intake valve at the first high-lift setting; and 
 controlling the intake valve from the first low-lift setting to the first high-lift setting if the estimated effective cylinder volume for air at the first low-lift setting is equal to the estimated effective cylinder volume for air at the first high-lift setting; and 
 
 subsequently transitioning the exhaust valve from the second low-lift setting to a second high-lift setting, comprising:
 controlling the variable valve actuation timing of the exhaust valve to a setting close to a maximum positive overlap position for the exhaust valve; 
 controlling the variable valve actuation timing of the intake valve to the setting close to the maximum positive overlap position for the intake valve; 
 comparing an estimated effective cylinder volume for residual gas corresponding to the variable valve actuation timing of the exhaust valve at the setting close to the maximum positive overlap position at the second low-lift setting to an estimated effective cylinder volume for residual gas corresponding to the variable valve actuation timing of the exhaust valve at the setting close to a positive overlap position at the second high-lift setting; and 
 controlling the exhaust valve from the second low-lift setting to the second high-lift setting if the estimated effective cylinder volume for residual gas at the second high-lift setting is greater than the estimated effective cylinder volume for residual gas at the second low-lift setting. 
 
 
 
     
     
       17. The method of  claim 15 , wherein the current intake valve lift setting is a first low-lift setting;
 wherein the current exhaust valve lift setting is a second low-lift setting; and 
 wherein determining the valve transition scheme further comprises:
 transitioning the intake valve from the first low-lift setting to a first high-lift setting, comprising:
 controlling the variable valve actuation timing of the intake valve to a calibrated setting corresponding to an estimated effective cylinder volume for air with the intake valve in the first low-lift setting being substantially equal to an estimated effective cylinder volume for air with the intake valve in the first high-lift setting; and 
 controlling the intake valve from the first low-lift setting to the first high-lift setting; and 
 
 subsequently transitioning the exhaust valve from the second low-lift setting to a second high-lift setting, comprising:
 controlling the variable valve actuation timing of the intake valve to a setting close to a maximum positive overlap position for the intake valve; 
 controlling the variable valve actuation timing of the exhaust valve to a calibrated setting corresponding to an estimated effective cylinder volume for residual gas with the exhaust valve in the second low-lift setting being substantially equal to an estimated effective cylinder volume for residual gas with the exhaust valve in the second high-lift setting; and 
 controlling the exhaust valve from the second low-lift setting to the second high-lift setting. 
 
 
 
     
     
       18. The method of  claim 15 , wherein the current intake valve lift setting is a first low-lift setting;
 wherein the current exhaust valve lift setting is a second low-lift setting; and 
 wherein determining the valve transition scheme further comprises:
 increasing the effective cylinder volume for air and decreasing the effective cylinder volume for residual gas by:
 controlling the variable valve actuation of the intake valve to a calibrated setting whereat the intake valve can be changed from the first low-lift setting to a first high-lift setting with substantially zero change to the effective cylinder volume for air; 
 changing the intake valve from the first low-lift setting to the first high-lift setting; 
 controlling the variable valve actuation of the exhaust valve and the variable valve actuation of the intake valve toward a maximum positive overlap position to a calibrated setting whereat the exhaust valve can be changed from the second low-lift setting to a second high-lift setting with substantially zero change to the effective cylinder volume for residual gas; 
 changing the exhaust valve from the second low-lift setting to the second high-lift setting; and 
 controlling the variable valve actuation of the exhaust valve based upon the desired engine operating state to control the effective cylinder volume for air and the effective cylinder volume for residual gas. 
 
 
 
     
     
       19. The method of  claim 15 , wherein the current exhaust valve lift setting is a low-lift setting;
 wherein the current intake valve lift setting is a first high-lift setting; and 
 wherein determining the valve transition scheme further comprises:
 transitioning the exhaust valve from the low-lift setting to a second high-lift setting, comprising:
 controlling the variable valve actuation timing of the exhaust valve to a calibrated setting corresponding to an estimated effective cylinder volume for residual gas with the exhaust valve in the second high-lift setting being substantially equal to an estimated effective cylinder volume for residual gas with the exhaust valve in the low-lift setting; and 
 
 controlling the exhaust valve from the low-lift setting to the second high-lift setting.